Autoantibodies from Single Circulating Plasmablasts React with Citrullinated Antigens and Porphyromonas gingivalis in Rheumatoid Arthritis

Song Li, Yangsheng Yu, Yinshi Yue, Hongyan Liao, Wanqin Xie, Jessica Thai, Ted R Mikuls, Geoffrey Milton Thiele, Michael J. Duryee, Harlan Sayles, Jeffrey B Payne, Lynell Warren Klassen, James Robert O'Dell, Zhixin Zhang, Kaihong Su

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Objective Anti-citrullinated protein antibodies (ACPAs) are highly specific for rheumatoid arthritis (RA). However, the molecular basis for ACPA production is still unclear. The purpose of this study was to determine if circulating plasmablasts from RA patients produce ACPAs and whether Porphyromonas gingivalis facilitates the generation of ACPAs. Methods Using a single-cell antibody cloning approach, we generated 217 and 110 monoclonal recombinant antibodies from circulating plasmablasts from 7 RA patients and 4 healthy controls, respectively. Antibody reactivity with citrullinated antigens was tested by a second-generation anti-cyclic citrullinated peptide (anti-CCP) kit and by enzyme-linked immunosorbent assays (ELISAs) against citrullinated human antigens. Antibody reactivity with P gingivalis was tested by ELISAs against outer membrane antigens (OMAs) and citrullinated enolase from P gingivalis. Results Approximately 19.5% of plasmablast-derived antibodies from anti-CCP-positive RA patients, but none from 1 anti-CCP-negative RA patient or the healthy controls, specifically recognized citrullinated antigens. The immunoglobulin genes encoding these ACPAs were highly mutated, with increased ratios of replacement mutations to silent mutations, suggesting the involvement of active antigen selection in ACPA generation. Interestingly, 63% of the ACPAs cross-reacted with OMAs and/or citrullinated enolase from P gingivalis. The reactivity of ACPAs against citrullinated proteins from P gingivalis was confirmed by immunoblotting and mass spectrometry. Furthermore, some germline-reverted ACPAs retained their reactivity with P gingivalis antigens but completely lost their reactivity with citrullinated human antigens. Conclusion These results suggest that circulating plasmablasts in RA patients produce ACPAs and that this process may be facilitated by anti-P gingivalis immune responses.

Original languageEnglish (US)
Pages (from-to)614-626
Number of pages13
JournalArthritis and Rheumatology
Volume68
Issue number3
DOIs
StatePublished - Mar 1 2016

ASJC Scopus subject areas

  • Immunology and Allergy
  • Rheumatology
  • Immunology

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